It is known to provide a centre console display device in a dashboard of a motor vehicle having side-by-side seating directly in front of the dashboard. The display device is visible to the driver and front seat passenger and may contain information such as navigation information, audio information, climate information and communication information.
A major failure mode of such a display device is known as sunlight washout. Sunlight washout refers to a reduction in display performance to and beyond the point of failure due to high ambient light levels. That is, under certain lighting conditions such as when direct sunlight is incident on the display, the information on the display cannot be read by a person viewing the display. The failure is due primarily to the optical properties and performance of the display itself, such as a brightness of illumination emitted by the display and a reflectance of the display to light incident thereon.
FIG. 1 is a schematic diagram showing a known LCD display device 1 mounted to the dashboard of a motor vehicle. The positions of eyes of a driver D and of a passenger P of the vehicle are shown. It can be seen that the eyes of the driver D view the display device 1 in a direction that is at an angle θ1 to a direction N normal to the display, the direction lying in a plane substantially normal to the plane of the device 1.
The eyes of the passenger P view the display device 1 along a direction that is at an angle θ2 to the direction N. θ1 and θ2 are typically in the range 30-35 degrees in a motor vehicle.
FIG. 2 is a plot of luminance of the LCD display 1 as a function of viewing angle. A central area of the plot labeled ML includes the direction N (FIG. 1) and shows the range of viewing angles over which the display 1 generates the maximum luminance values.
A circumferential edge of the plot corresponds to a direction substantially in the plane of the display 1 and the shading indicates that the display 1 generates the lowest values of luminance when viewed along a direction in this plane.
The range of viewing angles with which a passenger P and driver D typically view the display are superimposed on the plot in dotted lines and labeled P, D respectively. It can be seen that this range of viewing angles does not include the range of viewing angles ML at which maximum luminance from the display 1 is enjoyed. It is to be understood that this is because the driver D and passenger P do not view the display along a direction normal to the plane of the display 1.